A-mpdu preemption for time-critical ultra-low latency (ull) communications

ABSTRACT

Embodiments disclosed herein are directed to communicating time-critical ultra-low latency (ULL) data. An access point station (AP) communicates time-critical ULL data using aggregated MAC Protocol Data Unit (A-MPDU) preemption. When time-critical ULL data for a second associated STA (STA2) becomes available at a medium access control (MAC) layer of the AP during transmission of a physical layer protocol data unit (PPDU) to a first associate station (STA1), the AP may encode the time-critical ULL data in a new A-MPDU subframe for insertion before one of the A-MPDU subframes of the PPDU that has not yet been transmitted. The new A-MPDU subframe may be encoded to include zero-padding to set a size of the new A-MPDU subframe equal to a size of the A-MPDU subframe that has been preempted. The A-MPDU subframes 606 for STA1 may be encoded include a MAC address of the STA1 and the new A-MPDU subframe 608 may be encoded include a MAC address of the STA2.

TECHNICAL FIELD

Embodiments pertain to wireless communications. Some embodiments relateto wireless networks including wireless local area networks (WLANS)including those operating in accordance with the IEEE 802.11 standards.Some embodiments relate to wireless time-sensitive networks (TSN) andwireless time-sensitive networking (WTSN). Some embodiments pertain totime-critical ultra-low latency (ULL) data communication.

BACKGROUND

One issue with communicating data over a wireless network is Emergingtime-sensitive (TS) applications represent new markets for Wi-Fi.Industrial automation, robotics, AR/VR and HMIs (Human-MachineInterface) are example applications. Many time-sensitive applicationsrequire ultra-low latency (ULL) with minimal queuing and medium accessdelay within a wireless system. For instance, Programable LogicController (PLCs) may execute control loops requiring isochronous(cyclic) transmission of small time-critical (TC) packets (typically afew bytes) with cycles of 10's of microseconds. Furthermore,applications that need ULL typically also require very high reliability.The ULL requirement for TC packets practically imposes very highreliability requirements as multiple retransmissions (following thetypical Wi-Fi protocols) are not feasible.

Although IEEE 802.11ax has introduced triggered-based OFDMA operation,the overhead involved in the basic trigger-based data exchange within aTXOP is high, especially for small packet sizes. Many time-sensitiveapplications involve isochronous (cyclic) transmission of small packets(typically a few bytes) within very short cycles with high reliability.

Thus what is needed are communication techniques suitable fortime-sensitive applications that require lower overhead and arecompatible with legacy network communications (i.e., IEEE 802.11ax andprevious versions of the 802.11 standard). Thus, what is also needed isimproved techniques to communicate time-critical ULL data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an example network, in accordance with someembodiments.

FIG. 1B illustrates an enhanced wireless time sensitive networking(WTSN) medium access control/physical layer (MAC/PHY) configuration fora WTSN device, in accordance with some embodiments.

FIG. 2 illustrates a timing diagram of an enhanced WTSN timesynchronization, in accordance with some embodiments.

FIG. 3A illustrates a control channel access sequence, in accordancewith some embodiments.

FIG. 3B illustrates a combined channel access sequence, in accordancewith some embodiments.

FIG. 3C illustrates an on-demand channel access sequence, in accordancewith some embodiments.

FIG. 4A illustrates an EHT MU PPDU format, in accordance with someembodiments.

FIG. 4B illustrates an EHT TB PPDU format, in accordance with someembodiments.

FIG. 5 illustrates channel access delay associated with simultaneoustransmission and reception (STR) operations, in accordance with someembodiments.

FIG. 6 illustrates aggregated MAC Protocol Data Unit (A-MPDU) preemptionfor time-critical ultra-low latency (ULL) communications, in accordancewith some embodiments.

FIG. 7 illustrates a functional block diagram of a wirelesscommunication device, in accordance with some embodiments.

FIG. 8 illustrates a procedure for communicating time-critical ULL datausing A-MPDU preemption, in accordance with some embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

Embodiments disclosed herein are directed to communicating time-criticalultra-low latency (ULL) data. In some embodiments, an access pointstation (AP) communicates time-critical ULL data using aggregated MACProtocol Data Unit (A-MPDU) preemption. In these embodiments, whentime-critical ULL data for a second associated STA (STA2) becomesavailable at a medium access control (MAC) layer of the AP duringtransmission of a physical layer protocol data unit (PPDU) to a firstassociate station (STA1), the AP may encode the time-critical ULL datain a new A-MPDU subframe for insertion before one of the A-MPDUsubframes of the PPDU that has not yet been transmitted. In some ofthese embodiments, the new A-MPDU subframe may be encoded to includezero-padding to set a size of the new A-MPDU subframe equal to a size ofthe A-MPDU subframe that has been preempted. In some of theseembodiments, the A-MPDU subframes 606 for STA1 may be encoded include aMAC address of the STA1 and the new A-MPDU subframe 608 may be encodedinclude a MAC address of the STA2. These embodiments, as well as others,are described in more detail herein.

Reliable and deterministic communications between devices may berequired in some circumstances. One example may be time sensitivenetworking (TSN). TSN applications may require very low and boundedtransmission latency and high availability and may include a mix oftraffic patterns and requirements from synchronous data flows (e.g.,from sensors to a controller in a closed loop control system), toasynchronous events (e.g., a sensor detecting an anomaly in a monitoredprocess and sending a report right away), to video streaming for remoteasset monitoring and background IT/office traffic. Many TSN applicationsalso may require communication between devices with ultra-low latency(e.g., on the order of tens of microseconds).

Autonomous systems, smart factories, professional audio/video, andmobile virtual reality are examples of time sensitive applications thatmay require low and deterministic latency with high reliability.Deterministic latency/reliability may be difficult to achieve withexisting Wi-Fi standards (e.g., the IEEE 802.11 family of standards),which may focus on improving peak user throughput (e.g., the IEEE802.11ac standard) and efficiency (e.g., the IEEE 802.11ax standard).Extending the application of Wi-Fi beyond consumer-grade applications toprovide wireless TSN (WTSN) performance presents an opportunity to applyWi-Fi to Internet of things (IOT), and new consumer markets (e.g.,wireless virtual reality). The non-deterministic nature of the IEEE802.11 medium access control (MAC) layer in an unlicensed spectrum mayimpose challenges to expanding the application of Wi-Fi in this manner,especially when trying to guarantee reliability in comparison toEthernet TSN applications.

It may be desirable to enable time-synchronized and scheduled MAC layercommunications to facilitate time sensitive transmissions over Wi-Fi.The MAC may benefit from a more flexible control/management mechanism toadapt scheduling and/or transmission parameters (e.g., adapt amodulation and coding scheme and increase power) to control latency andto increase reliability. For example, changes in a wireless channel,such as interference or fading, may trigger retransmissions, which mayimpact the latency for time sensitive data due to increased channelthroughput. An access point (AP) may update station (STA) transmissionparameters to increase reliability (e.g., increase transmission power),which may require a transmission schedule update. An AP may also reducea number of STAs that share a given service period to provide morecapacity for retransmissions within a maximum required latency. Anotherexample may include high-priority data (e.g., random alarms/events in anindustrial control system), which may need to be reported with minimallatency, but cannot be scheduled a priori. Although regular beacons maybe used to communicate scheduling and other control/management updates,it may be desirable to have a more deterministic and flexible controlmechanism in future Wi-Fi networks that may enable fastermanagement/scheduling of a wireless channel to facilitate time sensitiveapplications with high reliability and efficiency.

It may also be desirable to ensure that devices in a network or extendedservice set (ESS) receive schedule updates and maintain a synchronizedschedule. Once a time sensitive transmission schedule is updated, alldevices may need to receive the updated schedule before the schedule maybecome applicable, otherwise the updated schedule may not be reliable(e.g., not all devices may properly follow the schedule). To meet therequirements of time sensitive traffic, it may be desirable to ensurethat all relevant devices comply with schedule updates regardless ofactive and sleep states of the devices.

To enable synchronization and scheduling, control/management frames maybe used. Control/management frames may share a channel with data frames.It may be desirable, however, to have a dedicated channel forcontrol/management frames that may be separate from a data channel. Inaddition, it may be desirable to have mechanisms to enable dynamiccontrol/management actions using controlled latency and highreliability. Something other than beacon transmissions by themselves maybe beneficial to enable dynamic and fast updates to operations requiredto maintain a quality of service for time sensitive applications.

To support such WTSN operations, it may be beneficial to redesign theMAC layer and physical layer (PHY) to improve efficiency and performancewithout needing to consider legacy behaviors or support backwardcompatibility while being able to coexist with legacy devices. Agreenfield mode may refer to a device that assumes that there are nolegacy (e.g., operating under previous protocol rules) stations (STAs)using the same channel. Thus, a device operating with a greenfield modemay operate under an assumption that all other STAs follow the same(e.g., newest) protocols, and that no legacy STAs are competing for thesame channel access. In some embodiments, an STA operating with agreenfield mode may at least assume that any legacy STAs that may existmay be managed to operate in a separate channel and/or time. However,operations with multiple access points (APs) may experienceinterference, latency, and/or other performance issues. For example, APsmay not all be aware of what other APs and STAs may be doing. Therefore,it may be desirable to define a greenfield Wi-Fi operation in a 6-7 GHzband or another frequency band, and thereby enable a time synchronizedscheduled access mode for multiple APs in the 6-7 GHz band or otherexisting frequency bands (e.g., 2.4 GHz, 5 GHz) of future Wi-Figenerations.

The design of a greenfield air interface may be governed by significantreliability and latency constraints imposed by WTSN operations. It maytherefore be desirable to efficiently design MAC and PHY communicationsto support WTSN applications. Legacy MAC/PHY operations may beasynchronous and may apply contention-based channel access and mayrequire significant overhead for backward compatibility that may beimportant for devices to coexist in unlicensed frequency bands. Suchlegacy MAC/PHY operations may be too inefficient to support timesensitive applications, especially as such traffic increases, but theymay still be used for non-time sensitive data or control traffic (e.g.in a legacy control channel).

While contention-free channel access mechanisms exist (e.g., pointcoordination function, hybrid coordination function controlled channelaccess), such mechanisms may lack the predictability required to supportWTSN operations, as the mechanisms may be stacked on a distributedcoordination function and may use polling operations with significantoverhead and other inefficient steps.

Device synchronization may use transmissions with significant overhead.For example, PHY headers may be included in some or all transmissionsbetween devices. For example, data frames and acknowledgement (ACK)frames may use legacy preambles that make the frames longer, reducingthe number of transmissions that may be accomplished during atransmission opportunity (TXOP). Synchronization that occurs up front(e.g., at the start of a TXOP) may allow for reduced overhead insubsequent transmissions, and therefore may reduce the resourcesrequired for some transmissions and may allow for more throughput andlower latency in a channel.

Example embodiments of the present disclosure relate to systems,methods, and devices for enhanced time sensitive networking for wirelesscommunications. In some embodiments, time sensitive control and datachannel operations may be enabled for IEEE 802.11 standards, includingfor future generations of IEEE 802.11 standards (e.g., beyond IEEE802.11ax, including 6-7 GHz communication bands, and/or in deploymentsin which it may be feasible to enable channel/band steering of an STAwith time sensitive requirements, such as in managed private networks.

In some embodiments, control information may be updated (e.g., usingscheduling) without interfering with time sensitive data, ensuringlatency and reliability guarantees. For example, a time sensitive datatransmission may be needed, and control information such as transmissionschedules may also need to be updated to facilitate subsequenttransmission. The control information updates may be sent andimplemented without interfering with the time sensitive datatransmissions.

In some embodiments, a time sensitive control channel (TSCCH) may bedefined by combining two approaches: a periodic approach and anon-demand approach. The period approach may include predefined controlslots. In the on-demand approach, an AP may define control slots asneeded. A TSCCH access mechanism may use contention-based or timesynchronized scheduled access procedures. Also, a wake-up signal may beused to allow delivery of time sensitive control/management informationto STAs across a network, reducing latency and allowing power save modesfor the STAs.

In some embodiments, a TSCCH may be in a different physical/logicalchannel from a data transmission. For example, a data transmission mayuse a data channel (e.g., in a 6-7 GHz band) while TSCCH may useseparate control channel in another band (e.g., 2.4 GHz or 5 GHz).

In some embodiments, use of a TSCCH operation and access mechanism mayallow improved flexibility and more deterministic opportunities for anAP to provide timely updates (e.g., schedules and control parameters)needed to manage latency and reliability, which may be beneficial insupporting time sensitive applications.

In some embodiments, a greenfield operation deployed in existing or newfrequency bands (e.g., 6-7 GHz) and other managed networks mayfacilitate improved management of Wi-Fi networks operating in scheduledmodes with time sensitive operations.

In some embodiments, it may be assumed that a Wi-Fi network may bemanaged and that there are no unmanaged nearby Wi-Fi STAs or networks.This assumption may be reasonable for time sensitive applications.

In some embodiments, it may be assumed that APs and STAs may synchronizetheir clocks to a master reference time. For example, STAs maysynchronize to beacons and/or may use time synchronization protocols(e.g., as defined by the IEEE 802.1AS standard or other synchronizationcapabilities defined in the 802.11 standard).

In one or embodiments, it may be assumed that an AP may define atime-synchronized scheduled mode. In some embodiments, a greenfield modemay apply to a 6-7 GHz frequency band, and the greenfield mode may applyto other bands (e.g., 2.4 GHz, 5 GHz) where support for legacy devicesmay not be required (e.g., in some private networks). A greenfield modemay be applied according to the following principles.

In some embodiments, a fully synchronized and scheduled operation may bedefined for a self-contained/synchronized transmission opportunity(S-TXOP) that may include a series of both uplink and downlinktransmissions. During an S-TXOP, an AP may maintain control of a mediumand may schedule access across predefined deterministic time boundaries.The use of an S-TXOP may maximize an amount of TSN traffic served whileproviding latency and reliability guarantees that support time sensitiveoperations with high efficiency.

In some embodiments, communication overheads related to synchronization,channel measurement and feedback, scheduling, and resource allocationmay be intelligently packed at the beginning of an S-TXOP and may allowsubsequent data transmissions to be extremely lightweight with minimaloverhead. For example, up-front synchronization may allow for devices tobe configured so that the devices do not need as much information as iscurrently provided in legacy headers. Instead, headers may be shorterbecause an S-TXOP has been coordinated among devices. The reducedoverhead may allow for more TSN traffic to be served while providingsufficient latency and reliability of transmissions.

In some embodiments, there may be flexibility to define deterministiccommunication boundaries within an S-TXOP to accommodate applicationsrequiring latency bounds in a sub-millisecond range, or other tight timeranges, for example.

In some embodiments, a multi-band framework may be leveraged to allowbackward compatibility and coexistence with legacy Wi-Fi applications. Anew greenfield mode as defined herein may be used for datacommunications, and minimal control may be required to sustain targetlatency, reliability, and throughput performance. Legacy modes and bandsmay be used to perform basic/long-term control and management tasks(e.g., non-time sensitive tasks) as well as time sensitive tasks.

In some embodiments, to reduce overhead for coexistence, a firsttransmission in an S-TXOP may include a legacy preamble to enablecoexistence with legacy devices.

In some embodiments, enhanced time sensitive networking may improveperformance over some existing wireless communications. For example,efficiency and latency may be improved, and the enhanced time sensitivenetworking may support a larger number of STAs for a given wirelessresource while meeting latency bounds for TSN applications. (e.g.,augmented virtual reality, industrial control, and autonomous systems).Enhanced time sensitive networking may allow coexistence with legacyWi-Fi operations by leveraging multi-band devices. Coexistence acrossnetworks operating in a greenfield mode as defined herein may be allowedby having better management and coordination across basic service sets(BSSs), which may be facilitated by higher layer management/coordinationprotocols.

In some embodiments, a number of assumptions may be used for thegreenfield mode of enhanced time sensitive networking. In someembodiments, WTSN STAs may be multi-band devices in which the MAC/PHYmay operate in a different band (e.g., 6-7 GHz) than the band of alegacy STA, which may operate in 2.4 GHz or 5 GHz bands.

In some embodiments, a fully managed Wi-Fi deployment scenario in whichother radio technology (e.g., legacy Wi-Fi or cellular) may not beexpected to operate in a same band where a WTSN STA may be operating. Insome embodiments, the enhanced time sensitive networking may be used inan indoor operating environment with relatively low mobility.

In some embodiments, a packet belonging to a TSN-grade application whenqueued at a WTSN STA may be dropped at a transmitter side if the packetdoes not get into air within a certain latency bound time.

The above descriptions are for purposes of illustration and are notmeant to be limiting. Numerous other examples, configurations,processes, etc., may exist, some of which are described in detail below.Example embodiments will now be described with reference to theaccompanying figures.

FIG. 1A is a diagram illustrating an example network environment, inaccordance with some embodiments. Wireless network 100 may include oneor more user devices 120 and one or more access point(s) (APs) 102,which may communicate in accordance with and compliant with variouscommunication standards and protocols, such as, Wi-Fi, TSN, WirelessUSB, P2P, Bluetooth, NFC, or any other communication standard. The userdevice(s) 120 may be mobile devices that are non-stationary (e.g., nothaving fixed locations) or may be stationary devices.

In some embodiments, the user devices 120 and AP 102 may include one ormore computer systems similar to that of the functional diagram of FIG.9 . One or more illustrative user device(s) 120 and/or AP 102 may beoperable by one or more user(s) 108. It should be noted that anyaddressable unit may be a station (STA). An STA may take on multipledistinct characteristics, each of which shape its function. For example,a single addressable unit might simultaneously be a portable STA, aquality-of-service (QoS) STA, a dependent STA, and a hidden STA. The oneor more illustrative user device(s) 120 and the AP(s) 102 may be STAs.The one or more illustrative user device(s) 120 and/or AP 102 mayoperate as a personal basic service set (PBSS) control point/accesspoint (PCP/AP). The user device(s) 120 (e.g., 124, 126, or 128) and/orAP 102 may include any suitable processor-driven device including, butnot limited to, a mobile device or a non-mobile, e.g., a static, device.For example, user device(s) 120 and/or AP 102 may include, a userequipment (UE), a station (STA), an access point (AP), a softwareenabled AP (SoftAP), a personal computer (PC), a wearable wirelessdevice (e.g., bracelet, watch, glasses, ring, etc.), a desktop computer,a mobile computer, a laptop computer, an ultrabook™ computer, a notebookcomputer, a tablet computer, a server computer, a handheld computer, ahandheld device, an internet of things (IoT) device, a sensor device, arobotic device, an actuator, a robotic arm, an industrial roboticdevice, a programmable logic controller (PLC), a safety controller andmonitoring device, a PDA device, a handheld PDA device, an on-boarddevice, an off-board device, a hybrid device (e.g., combining cellularphone functionalities with PDA device functionalities), a consumerdevice, a vehicular device, a non-vehicular device, a mobile or portabledevice, a non-mobile or non-portable device, a mobile phone, a cellulartelephone, a PCS device, a PDA device which incorporates a wirelesscommunication device, a mobile or portable GPS device, a DVB device, arelatively small computing device, a non-desktop computer, a “carrysmall live large” (CSLL) device, an ultra mobile device (UMD), an ultramobile PC (UMPC), a mobile internet device (MID), an “origami” device orcomputing device, a device that supports dynamically composablecomputing (DCC), a context-aware device, a video device, an audiodevice, an A/V device, a set-top-box (STB), a blu-ray disc (BD) player,a BD recorder, a digital video disc (DVD) player, a high definition (HD)DVD player, a DVD recorder, a HD DVD recorder, a personal video recorder(PVR), a broadcast HD receiver, a video source, an audio source, a videosink, an audio sink, a stereo tuner, a broadcast radio receiver, a flatpanel display, a personal media player (PMP), a digital video camera(DVC), a digital audio player, a speaker, an audio receiver, an audioamplifier, a gaming device, a data source, a data sink, a digital stillcamera (DSC), a media player, a smartphone, a television, a musicplayer, or the like. Other devices, including smart devices such aslamps, climate control, car components, household components,appliances, etc. may also be included in this list.

Any of the user device(s) 120 (e.g., user devices 124, 126, 128, 130,and 132), and AP 102 may be configured to communicate with each othervia one or more communications networks 135 and/or 140 wirelessly orwired. The user device(s) 120 may also communicate peer-to-peer ordirectly with each other with or without the AP 102. Any of thecommunications networks 135 and/or 140 may include, but not limited to,any one of a combination of different types of suitable communicationsnetworks such as, for example, broadcasting networks, cable networks,public networks (e.g., the Internet), private networks, wirelessnetworks, cellular networks, or any other suitable private and/or publicnetworks. Further, any of the communications networks 135 and/or 140 mayhave any suitable communication range associated therewith and mayinclude, for example, global networks (e.g., the Internet), metropolitanarea networks (MANs), wide area networks (WANs), local area networks(LANs), or personal area networks (PANs). In addition, any of thecommunications networks 135 and/or 140 may include any type of mediumover which network traffic may be carried including, but not limited to,coaxial cable, twisted-pair wire, optical fiber, a hybrid fiber coaxial(HFC) medium, microwave terrestrial transceivers, radio frequencycommunication mediums, white space communication mediums, ultra-highfrequency communication mediums, satellite communication mediums, or anycombination thereof.

Any of the user device(s) 120 (e.g., user devices 124, 126, 128, 130,and 132) and AP 102 may include one or more communications antennas. Theone or more communications antennas may be any suitable type of antennascorresponding to the communications protocols used by the user device(s)120 (e.g., user devices 124, 126, 128, 130, and 132), and AP 102. Somenon-limiting examples of suitable communications antennas include Wi-Fiantennas, Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards compatible antennas, directional antennas,non-directional antennas, dipole antennas, folded dipole antennas, patchantennas, multiple-input multiple-output (MIMO) antennas,omnidirectional antennas, quasi-omnidirectional antennas, or the like.The one or more communications antennas may be communicatively coupledto a radio component to transmit and/or receive signals, such ascommunications signals to and/or from the user devices 120 and/or AP102.

Any of the user device(s) 120 (e.g., user devices 124, 126, 128, 130,and 132), and AP 102 may be configured to perform directionaltransmission and/or directional reception in conjunction with wirelesslycommunicating in a wireless network. Any of the user device(s) 120(e.g., user devices 124, 126, 128, 130, and 132), and AP 102 may beconfigured to perform such directional transmission and/or receptionusing a set of multiple antenna arrays (e.g., DMG antenna arrays or thelike). Each of the multiple antenna arrays may be used for transmissionand/or reception in a particular respective direction or range ofdirections. Any of the user device(s) 120 (e.g., user devices 124, 126,128, 130, and 132), and AP 102 may be configured to perform any givendirectional transmission towards one or more defined transmit sectors.Any of the user device(s) 120 (e.g., user devices 124, 126, 128, 130,and 132), and AP 102 may be configured to perform any given directionalreception from one or more defined receive sectors.

MIMO beamforming in a wireless network may be accomplished using RFbeamforming and/or digital beamforming. In some embodiments, inperforming a given MIMO transmission, user devices 120 and/or AP 102 maybe configured to use all or a subset of its one or more communicationsantennas to perform MIMO beamforming.

Any of the user devices 120 (e.g., user devices 124, 126, 128, 130, and132), and AP 102 may include any suitable radio and/or transceiver fortransmitting and/or receiving radio frequency (RF) signals in thebandwidth and/or channels corresponding to the communications protocolsutilized by any of the user device(s) 120 and AP 102 to communicate witheach other. The radio components may include hardware and/or software tomodulate and/or demodulate communications signals according topre-established transmission protocols. The radio components may furtherhave hardware and/or software instructions to communicate via one ormore communication standards and protocols, such as, Wi-Fi, TSN,Wireless USB, Wi-Fi P2P, Bluetooth, NFC, or any other communicationstandard. In certain example embodiments, the radio component, incooperation with the communications antennas, may be configured tocommunicate via 2.4 GHz channels (e.g. 802.11b, 802.11g, 802.11n,802.11ax), 5 GHz channels (e.g. 802.11n, 802.11ac, 802.11ax), or 60 GHZchannels (e.g. 802.11ad). In some embodiments, non-Wi-Fi protocols maybe used for communications between devices, such as Bluetooth, dedicatedshort-range communication (DSRC), Ultra-High Frequency (UHF) (e.g. IEEE802.11af, IEEE 802.22), white band frequency (e.g., white spaces), orother packetized radio communications. The radio component may includeany known receiver and baseband suitable for communicating via thecommunications protocols. The radio component may further include a lownoise amplifier (LNA), additional signal amplifiers, ananalog-to-digital (A/D) converter, one or more buffers, and digitalbaseband.

When an AP (e.g., AP 102) establishes communication with one or moreuser devices 120 (e.g., user devices 124, 126, 128, 130 and/or 132), theAP 102 may communicate in a downlink direction and the user devices 120may communicate with the AP 102 in an uplink direction by sending framesin either direction. The user devices 120 may also communicatepeer-to-peer or directly with each other with or without the AP 102. Thedata frames may be preceded by one or more preambles that may be part ofone or more headers. These preambles may be used to allow a device(e.g., AP 102 and/or user devices 120) to detect a new incoming dataframe from another device. A preamble may be a signal used in networkcommunications to synchronize transmission timing between two or moredevices (e.g., between the APs and user devices).

In some embodiments, and with reference to FIG. 1A, an AP 102 maycommunicate with user devices 120. The user devices 120 may include oneor more wireless devices (e.g., user devices 124, 132) and one or morewireless TSN devices (e.g., user devices 126 128, 130). The user devicesmay access a channel in accordance with medium access control (MAC)protocol rules or any other access rules (e.g., Wi-Fi, Bluetooth, NFC,etc.). It should be noted that reserving a dedicated TSN channel andcontrolling access to it may also be applicable to cellular systems/3GPPnetworks, such as LTE, 5G, or any other wireless networks. The wirelessTSN devices may also access a channel according to the same or modifiedprotocol rules. However, the AP 102 may dedicate certain channels orsub-channels for TSN applications that may be needed by the one or morewireless TSN devices (e.g., user devices 126, 128, and 130), and mayallocate other channels or sub-channels for the non-TSN devices (e.g.,user devices 124 and 132).

In some embodiments, AP 102 may also define one or more access rulesassociated with the dedicated channels. A channel may be dedicated forTSN transmissions, TSN applications, and TSN devices. For example, userdevice 126 may access a dedicated TSN channel for TSN transmissions. TSNtransmissions may include transmissions that have very low transmissionlatency and high availability requirements. Further, the TSNtransmissions may include synchronous TSN data flows between sensors,actuators, controllers, robots, in a closed loop control system. The TSNtransmissions require reliable and deterministic communications. Achannel may be accessed by the user device 126 for a number of TSNmessage flows and is not limited to only one TSN message flow. The TSNmessage flows may depend on the type of application messages that arebeing transmitted between the AP 102 and the user device 126.

In some embodiments, while frequency planning and channel management maybe used to allow AP 102 to collaborate with neighboring APs (not shown)to operate in different channels, the efficiency and feasibility ofreserving multiple non-overlapping data channels for time sensitiveapplications may be improved. It may be desirable to limit the amount ofresources reserved for time sensitive data through efficient channelreuse. If multiple devices (e.g., user devices 124, 126, 128, 130, 132)share a dedicated channel for time sensitive data transmissions,interference among multiple transmissions may be reduced with enhancedcoordination between the devices and one or more APs (e.g., AP 102). Forexample, overlap and interference of control transmissions (e.g., abeacon), downlink data transmissions, and uplink data transmissions maybe reduced with enhanced coordination. Such enhanced coordination formultiple APs may enable more efficient channel usage while also meetinglatency and reliability requirements of time sensitive applications. Forexample, if control transmissions are not received and interpretedproperly, time sensitive operations may not be scheduled properly,and/or may interfere with other transmissions, possibly causingoperational errors.

In some embodiments, AP 102 may include WTSN controller functionality(e.g., a wireless TSN controller capability), which may facilitateenhanced coordination among multiple devices (e.g., user devices 124,126, 128, 130, 132). AP 102 may be responsible for configuring andscheduling time sensitive control and data operations across thedevices. A wireless TSN (WTSN) management protocol may be used tofacilitate enhanced coordination between the devices, which may bereferred to as WTSN management clients in such context. AP 102 mayenable device admission control (e.g., control over admitting devices toa WTSN), joint scheduling, network measurements, and other operations.

In some embodiments, AP 102's use of WTSN controller functionality mayfacilitate AP synchronization and alignment for control and datatransmissions to ensure latency with high reliability for time sensitiveapplications on a shared time sensitive data channel, while enablingcoexistence with non-time sensitive traffic in the same network.

In some embodiments, AP 102 and its WTSN coordination may be adopted infuture Wi-Fi standards for new bands (e.g., 6-7 GHz), in whichadditional requirements of time synchronization and scheduled operationsmay be used. Such application of the WTSN controller functionality maybe used in managed Wi-Fi deployments (e.g., enterprise, industrial,managed home networks, etc.) in which time sensitive traffic may besteered to a dedicated channel in existing bands as well as new bands.

In some embodiments, it may be assumed that a Wi-Fi network may bemanaged, and that there are no unmanaged Wi-Fi STAs/networks nearby.

In some embodiments, it may be assumed that APs and STAs may synchronizetheir clocks to a master reference times (e.g., STAs may synchronize tobeacons and/or may use time synchronization protocols as defined in theIEEE 802.1AS standard).

In some embodiments, it may be assumed that APs and STAs may operateaccording to a time synchronized scheduled mode that may also apply tonew frequency bands (e.g., 6-7 GHz), for which new access protocols andrequirements also may be proposed.

In some embodiments, a WTSN domain may be defined as a set of APs (e.g.,AP 102) and STAs (e.g., user devices 124, 126, 128, 130, and 132) thatmay share dedicated wireless resources, and therefore may need tooperate in close coordination, at a level of control and time sensitivedata scheduling, to ensure latency and reliability guarantees. DifferentAPs in the same network may form different WTSN domains.

In some embodiments, the WTSN management protocol may be executed over awired (e.g., Ethernet) TSN infrastructure that may provide TSN gradetime synchronization accuracy and latency guarantees. The WTSNmanagement protocol may also be executed using wireless links (e.g., awireless backhaul, which may include Wi-Fi or WiGig links through one ormultiple hops). An Ethernet TSN interface may be replaced by a wirelessinterface (e.g., and 802.11 MAC and/or physical layer PHY). An operationof a second wireless interface may also be managed by AP 102 to avoidinterference with an interface used for communication with timesensitive user STAs (e.g., user devices 126, 128, and 130).

In some embodiments, AP 102 may perform admission control and schedulingtasks. To complete an association procedure for an STA with timesensitive data streams (e.g., user device 130), the STA may requestadmission from AP 102. AP 102 may define which APs may be in a WTSNdomain and may determine the admission of new time sensitive datastreams based on, for example, available resources and userrequirements. AP 102 may create and/or update a transmission schedulethat may include time sensitive operations and/or non-time sensitiveoperations, and the schedule may be provided to admitted user devices.AP 102 may be responsible for executing the schedule according to timesensitive protocols defined, for example, at 802.11 MAC/PHY layers.

In some embodiments, AP 102 may perform transmission schedule updates.AP 102 may update a transmission schedule for time sensitive data andmay send transmission schedule updates to STAs and/or other APs duringnetwork operation. A transmission schedule update may be triggered bychanges in wireless channel conditions at different APs and/or STAswithin a common WTSN domain. The condition changes may include increasedinterference, new user traffic requests, and other network and/oroperational changes that may affect a WTSN domain.

In some embodiments, AP 102 may collect measurement data from otherdevices in a WTSN domain. The measurement data may be collected fromtime sensitive and/or non-time sensitive devices. AP 102 may maintaindetailed network statistics, for example, related to latency, packeterror rates, retransmissions, channel access delay, etc. The networkstatistics may be collected via measurement reports sent from STAs. AP102 may use network statistics to proactively manage wireless channelusage to allow for a target latency requirement to be satisfied. Forexample, measurements may be used to determine potential channelcongestion and to trigger a change from a joint transmission schedulemode to a mode in which APs may allocate a same slot to multiplenon-interfering STAs that may be leveraging spatial reuse capabilities.

It is understood that the above descriptions are for purposes ofillustration and are not meant to be limiting.

FIG. 1B illustrates an enhanced WTSN MAC/PHY configuration for a WTSNdevice 150, in accordance with some embodiments.

In some embodiments, the WTSN device 150 may include a multibandoperation framework 152, legacy channel access functions 154, legacy PHY156, management, long-term control, and non-time sensitive traffic 158,coordinated synchronous access function (CSAF) 160, WTSN greenfield/PHY162, and TSN traffic, short-term control signaling 164.

In some embodiments, the multiband operation framework 152 may allowWTSN device 150 to perform multiband operations. For example, someoperations may be performed in one frequency band, while otheroperations may be performed in another frequency band. One frequencyband may include a control channel, and another frequency band mayinclude separate data channels.

In some embodiments, to provide for both WTSN and non-TSN operations,the WTSN device 150 may include a link for management, long-termcontrol, and non-time sensitive traffic 158, and a link for TSN trafficand short-term control signaling 164. To support the management,long-term control, and non-time sensitive traffic 158, WTSN device 150may include legacy channel access functions 154. Legacy channel accessfunctions 154 may include a distributed coordination function (DCF),hybrid coordination function controlled channel access (HCF), and otherchannel access functions. The management, long-term control, andnon-time sensitive traffic 158 may also be supported by a legacy PHY 156(e.g., on a 2.4 GHz or 5 GHz frequency). Long-term control may includebeacon transmissions, network association, security procedures, andother control traffic. Short-term control may include radiosynchronization (e.g., time-frequency synchronization), scheduling,channel feedback, and other control traffic.

In some embodiments, to support the TSN traffic, short-term controlsignaling 164, WTSN device 150 include the CSAF 160 and the WTSNgreenfield/PHY 162. The CSAF 160 may use a central coordinator at WTSNdevice 150 (e.g., AP 102 of FIG. 1A) to maintain a MAC/PHY levelsynchronization between the WTSN device 150 and non-AP STAs during anS-TXOP. The WTSN device 150 may control access to wireless media in ascheduled fashion in time, frequency, and spatial dimensions. With aninfrastructure for a basic service set (BSS) for WTSN, during an S-TXOP,all WTSN STAs may need to adhere to the MAC/PHY synchronization at alltimes.

In some embodiments, when WTSN STAs (e.g., user device 126, user device128, user device 130 of FIG. 1A) are not standalone devices,WTSN-capable devices may associate with a network using a legacy link(e.g., legacy channel access functions 154, legacy PHY 156, andmanagement, long-term control, non-time sensitive traffic 158 of FIG.1B). During association, a WTSN STA may indicate its capability andinterest to join a WTSN operation mode. Through the legacy link, amultiband AP (e.g., AP 102 of FIG. 1A) may instruct the WTSN-capable STAto configure the WTSN STA's MAC/PHY on designated band. The WTSN MAC inthe WTSN STA may achieve MAC/PHY synchronization and successfully readinitial control and synchronization information in a synchronization andconfiguration frame (SCF) received from the AP in a WTSN band. Throughthe legacy link, the AP and STA may complete the association process byexchanging management frames. This process may be referred to asassociating or establishing a channel/connection with a device.

In some embodiments, some long-term parameters and control signalsrelated to a WTSN MAC/PHY operation may be conveyed from a WTSN AP toWTSN non-AP STAs through the legacy link.

In some embodiments, the legacy link may also be used for admissioncontrol and/or inter-BSS coordination, and the multiband operationframework 152 may be used to direct TSN traffic (e.g., TSN traffic,short-term control signaling 164) to the WTSN MAC/PHY (e.g., WTSNGreenfield/PHY 162). The WTSN MAC/PHY may provide functionality tosupport ultra-low and near-deterministic packet latency (e.g., onemillisecond or less) with virtually no jitter in a controlledenvironment. Latency may be measured from a time when a logical linkcontrol (LLC) MAC service data unit (MDSU) enters a MAC sublayer at atransmitter to a time when the MDSU is successfully delivered from theMAC sublayer to an LLC sublayer on a receiver.

In some embodiments, WTSN operations may be facilitated by a synchronousand coordinated MAC/PHY operation during an S-TXOP between a WTSN AP andone or more non-AP WTSN STAs in a BSS infrastructure.

It is understood that the above descriptions are for purposes ofillustration and are not meant to be limiting.

FIG. 2 illustrates an timing diagram 200 of an enhanced WTSN timesynchronization, in accordance with some embodiments. Referring to FIG.2 , there is shown uplink and downlink data frame flows between AP 202and a TSN device 204. For example, TSN device 204 may receive downlinkdata frames from AP 202 and may send uplink data frames to AP 202. Inone embodiment, the WTSN time synchronization may be utilized forpersistent scheduling for synchronous transmission from TSN device 204to AP 202.

In some embodiments, during a beacon period 206 (e.g., 100× cycle time),AP 202 may transmit or receive during one or more service periods 208that comprise the beacon period 206. For example, service periods 208may span 1 millisecond or some other time during which one or moretransmissions may be made. A cycle time is a parameter that may beconfigured based on a service and/or latency requirements of one or moreapplications. For example, an STA application may generate packets in asynchronous/periodic pattern (e.g., of 1 millisecond cycles), andpackets generated at the beginning of a cycle may need to be deliveredwithin the cycle.

In some embodiments, AP 202 may send a control frame, such as a beacon210 during a service period 208 at the beginning of beacon period 206.During TXOP 212, TXOP 214, TXOP 216, TXOP 218, TXOP 220, TXOP 220, TXOP222, and TXOP 224, AP 202 may send or receive frames to/from TSN device204. At the conclusion of beacon period 206, a new beacon period maybegin with AP 202 sending beacon 226. In some embodiments, the controlframe may be a trigger frame. In these embodiments, the control framemay be used to initiate a sequence of multiple transmissions within aperiod that repeats, as further described herein.

In some embodiments, any of TXOP 212, TXOP 214, TXOP 216, TXOP 218, TXOP220, TXOP 220, TXOP 222, and TXOP 224 may include restricted orunrestricted service periods, time sensitive service periods, ornon-time sensitive service periods. TXOP 212, TXOP 214, TXOP 216, TXOP218, TXOP 220, TXOP 220, TXOP 222, and TXOP 224 may comprise one or moreservice periods 208.

It is understood that the above descriptions are for purposes ofillustration and are not meant to be limiting.

FIG. 3A illustrates an control channel access sequence 300, inaccordance with some embodiments. In some embodiments, AP 302 may be aWTSN device (e.g., WTSN device 150 of FIG. 1B) in communication with STA304, which may be another WTSN device. AP 302 and STA 304 may use aTSCCH 306 and a TSDCH 308 to transmit both control/management frames anddata frames.

In some embodiments, a beacon period 310 (e.g., 100× cycle time) maybegin with AP 302 sending beacon 312. Later in beacon period 310, AP 302may send short beacon 314, short beacon 316, short beacon 318, or anynumber of short beacons supported by the beacon period 310. At the endof beacon period 310, another beacon 320 may be sent by AP 302. Beacon312, short beacon 314, short beacon 316, short beacon 318, and/or beacon320 may provide control/management frames to STA 304 in TSCCH 306.

In some embodiments, TSCCH 306 and TSDCH 308 may be divided into cycles324 which may span a cycle time 326 (e.g., 1 ms). Beacon 312, shortbeacon 314, short beacon 316, short beacon 318, and/or beacon 320 maynot require an entire cycle 324.

In some embodiments, TSCCH 306 and TSDCH 308 may be logical channelsdefined within an existing or new physical channel/frequency band. TSCCH306 may be defined within a primary channel, while TSDCH 308 may bedefined in a secondary or dedicated TS channel, possibly in anotherfrequency band. TSCCH 306 may be used for time sensitive access undercontrol of AP 302. TSDCH 308 may be defined in an existing or new band(e.g., 6-7 GHz).

In some embodiments, configurations for TSCCH 306 and/or TSDCH 308 maybe transmitted as information elements in beacon 312, short beacon 314,short beacon 316, short beacon 318, and/or beacon 320. Theconfigurations may provide information identifying the correspondingphysical channels used for TSCCH 306 and TSDCH 308.

In some embodiments, TSCCH 306 may be defined as periodic resources(e.g., time-frequency slots) for exchanging control frames. Defining aperiodic interval for control frames may be important to enable timesensitive STAs (e.g., STA 304) to schedule time sensitive data andcontrol actions without conflicts (e.g., conflicts with other devices).

In some embodiments, TSCCH 306 may be used to transmit regular beacons(e.g., beacon 312, beacon 320) and short beacons (e.g., short beacon314, short beacon 316, short beacon 318), which may include a subset ofinformation transmitted of regular beacons (e.g., an updatedtransmission schedule or bitmap of restricted time sensitive serviceperiods). Short beacon transmissions may be scheduled in predefinedintervals (e.g., fractions of beacon period 310). Other managementframes may also be transmitted in TSCCH 306, such as associationrequest/response frames, timing measurements, and channel feedbackmeasurement frames.

In some embodiments, access to TSCCH 306 may use contention-based TSNsequence 300. Contention-based TSN sequence 300 may follow a legacycarrier-sense multiple access (CSMA)-based IEEE 802.11 MAC protocol. Forexample, when TSCCH 306 is defined as the operating/primary channel, AP302 may contend for TSCCH 306 using enhanced distributed channel access(EDCA) to transmit beacon (e.g., beacon 312, beacon 320) and shortbeacons (e.g., short beacon 314, short beacon 316, short beacon 318) atpredefined intervals. TSCCH control frames (e.g., beacon 312, shortbeacon 314, short beacon 316, short beacon 318, and/or beacon 320) mayinclude information to support a time synchronized scheduled access inTSDCH 308. Such operation may enable time sensitive operations forlegacy Wi-Fi systems in which TSCCH 306 may provide an anchor for TSDCH308 (e.g., time synchronized and schedule) in one or more restrictedchannels and/or frequency bands.

In some embodiments, access to TSCCH 306 may use a time-synchronizedaccess method. TSCCH 306 may be defined as periodic scheduled resources(e.g., time slots) for regular beacons (e.g., beacon 312, beacon 320)and short beacons (e.g., short beacon 314, short beacon 316, shortbeacon 318) using time-synchronized access. Access to time slots (e.g.,cycles 324) may still be based on contention (e.g., CSMA) or may bescheduled. For example, slots may be reserved for beacons and shortbeacons, which may be transmitted periodically (e.g., every fifth slot).TSCCH 306 may also be aligned with TSDCH 308 timing. TSCCH time slotsreserved for beacons and/or short beacons may be announced in regularbeacons so that newly admitted STAs (e.g., STA 304) may discover TSCCH306 parameters. All STAs may be required to adhere to timesynchronization across channels and ensure TXOPs do not overlap withscheduled TSCCH slots. In addition, all STAs may be required to listento TSCCH 306 during scheduled beacon/short beacon slots to make sure theSTAs receive those beacons/short beacons. Such operation may provide amore deterministic operation as timing of each TSCCH 306 may becontrolled and collisions may be avoided through efficient scheduling.

In some embodiments, remaining time of TSCCH slots (e.g., cycles 324)occupied by a beacon/short beacon may be used to exchange othercontrol/management frames. In some embodiments, AP 302 may transmitunicast control/management frames to STA 304 using TSDCH 308 providedthat the control/management frames do not interfere with time sensitivedata.

It is understood that the aforementioned example is for purposes ofillustration and not meant to be limiting.

FIG. 3B illustrates an combined channel access sequence 340, inaccordance with some embodiments. In some embodiments, AP 342 may be aWTSN device (e.g., WTSN device 150 of FIG. 1B) in communication with STA344, which may be another WTSN device. AP 342 and STA 344 may usechannel 346 to transmit both control/management frames and data frames.

In some embodiments, a beacon period 348 (e.g., 100× cycle time) havingone or more cycles 350 may begin with AP 342 sending beacon 352. Laterin beacon period 348, AP 342 and/or STA 344 may send one or more dataframes 354. AP 342 may send short beacon 356. AP 342 and/or STA 344 maysend one or more data frames 358. AP 342 may send short beacon 360. AP342 and/or STA 344 may send one or more data frames 362. AP 342 may sendshort beacon 364. AP 342 and/or STA 344 may send one or more data frames366. After beacon period 348 has concluded, AP 342 may send anotherbeacon 368 to begin another beacon period. The beacons (e.g., beacon352, short beacon 356, short beacon 360, short beacon 364, and beacon368) may be sent in channel 346. The one or more data frames (e.g., oneor more data frames 354, one or more data frames 358, one or more dataframes 362, and one or more data frames 366) may be sent in the channel346.

In some embodiments, channel 346 may be divided into cycles 350 whichmay span a cycle time 369 (e.g., 1 ms). Beacon 352, short beacon 356,short beacon 360, short beacon 364, and beacon 368 may not require anentire cycle 350. The one or more data frames (e.g., one or more dataframes 354, one or more data frames 358, one or more data frames 362,and one or more data frames 366) may use one or more cycles 350 and mayuse partial cycles 350.

In some embodiments, channel 346 may be a physical channel that includesa TSCCH and TSDCH. Using cycles 350, control/management frames (e.g.,beacon 352, short beacon 356, short beacon 360, short beacon 364, andbeacon 368) and data frames (e.g., one or more data frames 354, one ormore data frames 358, one or more data frames 362, and one or more dataframes 366) may be scheduled to avoid overlapping/conflictingtransmissions. Such enhanced coordination may facilitate WTSNcommunications which meet the latency and reliability requirements ofWTSN operations.

It is understood that the aforementioned example is for purposes ofillustration and not meant to be limiting.

FIG. 3C illustrates an on-demand channel access sequence 370, inaccordance with some embodiments. In some embodiments, AP 372 may be aWTSN device (e.g., WTSN device 150 of FIG. 1B) in communication with STA374, which may be another WTSN device. AP 372 and STA 374 may usechannel 376 to transmit both control/management frames and data frames.

In some embodiments, a beacon period 378 (e.g., 100× cycle time) havingone or more cycles 380 may begin with AP 372 sending beacon 382. Laterin beacon period 378, AP 372 and/or STA 374 may send one or more dataframes 384. AP 372 may send short beacon 386. AP 372 and/or STA 374 maysend one or more data frames 388. AP 372 may send short beacon 390. AP372 and/or STA 374 may send one or more data frames 392. After beaconperiod 378 has concluded, AP 372 may send another beacon 394 to beginanother beacon period. The beacons (e.g., beacon 382, short beacon 386,short beacon 390, and beacon 394) may be sent in channel 376. The one ormore data frames (e.g., one or more data frames 384, one or more dataframes 388, and one or more data frames 392) may be sent in the channel376.

In some embodiments, AP 372 may send control/management frames (e.g.,beacon 382, short beacon 386, short beacon 390, and beacon 394) ondemand using resources such as time slots (e.g., cycles 380) that maynot be reserved for time sensitive data.

FIG. 4A illustrates an EHT MU PPDU format, in accordance with someembodiments. The EHT MU PPDU format used for transmission to one or moreusers. The PPDU is not a response to a triggering frame. In the EHT MUPPDU, the EHT-SIG field is present.

FIG. 4B illustrates an EHT TB PPDU format, in accordance with someembodiments. The EHT TB PPDU format is used for a transmission that is aresponse to a triggering frame from an AP. In the EHT TB PPDU, theEHT-SIG field is not present and the duration of the EHT-STF field istwice the duration of the EHT-STF field in the EHT MU PPDU.

To increase the overall throughput of Wi-Fi devices, transmitopportunity (TXOP) and frame aggregation was introduced in 802.11n andsubsequent standards. This aggregation makes PPDU data payload muchbigger and therefore occupies a much longer airtime.

Although frame aggregation helps improve throughput and reduce averagelatency for a pair of STAs, it can result in a much higher worst-caselatency for a 3rd party STA waiting for the wireless medium to be idledue to a much longer airtime occupied by a long aggregated PPDU betweenthe pair of STAs. Time-sensitive frames may experience a higher latencyif the channel is occupied by a long PPDU transmission by other devicesfrom the same BSS or overlapping BSS (OBSS).

With the introduction of multiple link capability in 802.11be, thisproblem can be mitigated if a client device supports simultaneoustransmission and reception (STR) and if there is at least one link idle.However, this problem still exists if both two channels are occupied byany ongoing transmission from the same or overlapping BSS (OBSS) asshown in FIG. 5 . FIG. 5 illustrates channel access delay associatedwith simultaneous transmission and reception (STR) operations, inaccordance with some embodiments.

In some embodiments, a physical layer protocol data unit may be aphysical layer conformance procedure (PLCP) protocol data unit (PPDU).In some embodiments, the AP and STAs may communicate in accordance withone of the IEEE 802.11 standards. IEEE 802.11-2016 is incorporatedherein by reference. IEEE P802.11-REVmd/D2.4, August 2019, and IEEEdraft specification IEEE P802.11ax/D5.0, October 2019 are incorporatedherein by reference in their entireties. In some embodiments, the AP andSTAs may be directional multi-gigabit (DMG) STAs or enhanced DMG (EDMG)STAs configured to communicate in accordance with IEEE 802.11ad standardor IEEE draft specification IEEE P802.11ay, February 2019, which isincorporated herein by reference.

FIG. 6 illustrates A-MPDU preemption for time-critical ultra-low latency(ULL) communications, in accordance with some embodiments. Someembodiments are directed to an access point station (AP) configured forcommunicating time-critical ultra-low latency (ULL) data. In theseembodiments, the AP may be configured to encode a physical layerprotocol data unit (PPDU) 602 (see FIG. 6 ) for transmission to a firstassociated non-AP station (STA1). The PPDU may comprising a physicallayer (PHY) preamble 604 followed by a sequence of aggregated MACProtocol Data Unit (A-MPDU) subframes 606, 608, 610, etc., followed byend-of-file (EOF) padding 612. The AP may initiate transmission of thePPDU. In these embodiments, when time-critical ultra-low latency (ULL)data for a second associated STA (STA2) becomes available at a mediumaccess control (MAC) layer from an upper layer of the AP duringtransmission of the PPDU, the AP may be configured to encode thetime-critical ULL data in a new A-MPDU subframe 618 and insert the newA-MPDU subframe 618 before one of the A-MPDU subframes of the PPDUs thathas not yet been transmitted (i.e., before A-MPDU subframe 608). Inthese embodiments, the AP may complete transmission of the PPDU 602 withthe new A-MPDU subframe 618 followed by all but one of the remainingA-MPDU subframes for the STA1.

In these embodiments, when time-critical ULL data for another STA (i.e.,STA2) becomes available after transmission of a PPDU is initiated, anA-MPDU subframe of the PPDU may be preempted or delayed (i.e., A-MPDUsubframe 608) with an A-MPDU subframe that includes the time-criticalULL data. In these embodiments, new A-MPDU subframe 618 with thetime-critical ULL data is included before A-MPDU subframe 608. In theseembodiments, the last A-MPDU subframe of the PPDU for the STA1 may notbe able to be transmitted since the PPDU is not changed. As illustratedin FIG. 6 , A-MPDU subframe n 618 is now encoded for time-critical ULLdata and is intended for STA2.

In some embodiments, the new A-MPDU subframe 618 may be encoded toinclude zero-padding to set a size of the new A-MPDU subframe 618 equalto a size of the A-MPDU subframe 608 that has been preempted. In theseembodiments, the size of the new A-MPDU subframe 618 may be kept equalto the size of the preempted A-MPDU subframes 608. When thetime-critical ULL data is smaller/less than the data in the preemptedA-MPDU subframe 608, zero padding is used to make the sizes equal.

In some embodiments, the AP may also be configured to encode the EHT-SIGof the PHY preamble 604 to include association identifier (AID) of onlythe STA1, encode the A-MPDU subframes 606 for the STA1 to include a MACaddress of the STA1, and encode the new A-MPDU subframe 608 for the STA2to include a MAC address of the STA2. In these embodiments, the PPDU maybe encoded as single user PPDU (SU PPDU) (i.e., the single user beingSTA1)). In these embodiments, the time-critical ULL STA (i.e., STA2) mayhave been previously instructed by the AP to decode PPDUs for STA1 tolook for time-critical ULL data. In these embodiments, the time-criticalULL STA (STA2) may be bonded with STA1 for reception of time-criticalULL data, although the scope of the embodiments is not limited in thisrespect.

In some embodiments, the AP may be further configured to encode theA-MPDU subframes 606, 608, 610 for the STA1 and indicate ACK if desired(i.e., the acknowledgement field for these subframes may be set to ACKor NACK). The AP may also encode the new A-MPDU subframe 618 for theSTA2 and indicate NACK for the new A-MPDU subframe 618. In theseembodiments, the ACK policy for each A-MPDU subframe may individuallyset.

In some embodiments, the AP may further be configured to encode the newA-MPDU subframe using one or more physical layer (PHY) parameters (e.g.,an MCS indicated in a signal field (SIG) e.g., one of the HE-SIG-A fieldand SIG field of the PHY preamble of the PPDU. In these embodiments, aPHY layer change is avoided since at least some of the physical layerparameters are unchanged.

In some embodiments, the PPDU may be encoded as a single user (SU) PPDUfor the STA1, although the scope of the embodiments is not limited inthis respect. In some embodiments, the PPDU may be a MU PPDU.

In some embodiments, prior to initiating transmission of the PPDU to theSTA1, the AP and the STA2 have established a time-sensitive networkingapplication that includes communication of the time-critical ULL datatherebetween. In some embodiments, as part of establishment of thetime-sensitive networking application, the AP may have indicated to theSTA2 to decode PPDUs for STA1 for possible transmission of thetime-critical ULL data for STA2 (e.g., STA1 and ST2 are bonded). Inthese embodiments, prior to initiating transmission of the PPDU to theSTA1, the AP may acquire a TXOP for transmission of the PPDU. In theseembodiments, STA1 may be a bonded STA. In these embodiments,particularly in the case of a-periodic ULL data, the STA2 (thetime-critical ULL STA) may need to decode each A-MPDU subframe of thePPDU with the AID of the bonded STA in the preamble (such as STA1's AIDin the EHT-SIG) to determine if the A-MPDU subframe has a MAC address ofSTA2. When the subframe has the MAC address of STA2, STA2 may furtherdecode the A-MPDU subframe to extract the time-critical ULL data. In thecase of periodic time-critical ULL data, the STA2 may know apriori whichA-MPDU subframe of the PPDU includes the time-critical ULL data andtherefore it may not need to decode each A-MPDU subframe of the PPDU todetermine which A-MPDU subframe is intended for the STA2.

In some embodiments, the time-critical ULL data for the STA2 may bereceived at the MAC layer from an application upper layer of the AP. Inthese embodiments the AP may initiate transmission of the PPDU to theSTA1 when there is no time-critical ULL data available for the STA2 in atransmission queue. In these embodiments, when the time-critical ULLdata for the STA2 is received at the MAC layer from the applicationupper layer of the AP after transmission of the PPDU has been initiated,the AP may delay one of the A-MPDU subframes for the STA1 and insert thenew A-MPDU subframe in the PPDU that includes that the time-critical ULLdata for the STA2.

In some embodiments, the time-critical ULL data has a latencyrequirement of less than or equal to one millisecond (ms), although thescope of the embodiments is not limited in this respect.

In some embodiments, the AP may insert the new A-MPDU subframe 618 intothe PPDU when transmission of the time-critical ULL data aftertransmission the PPDU without the time-critical ULL data would exceedthe latency requirement (i.e., to meet the latency requirement, thetime-critical ULL data needs to be transmitted within the PPDU that iscurrently being transmitted). In these embodiments, the AP may refrainfrom inserting the new A-MPDU subframe 618 when transmission of thetime-critical ULL data after transmission the PPDU would not exceed thelatency requirement (i.e., the latency requirement can be met bytransmission of the time-critical ULL data subsequent to transmission ofthe PPDU. In some embodiments, the latency requirement for time-criticalULL data is less than or equal to one millisecond (lms) with a sizelimit of 100 bytes, although the scope of the embodiments is not limitedin this respect.

In some embodiments, after transmission of the PPDU is initiated andwhen the time-critical ULL data for the STA2 does not becomes availableduring transmission of the PPDU, the processing circuitry is configuredto refrain from encoding the time-critical ULL data in the new A-MPDUsubframe. The AP may also refrain from inserting the new A-MPDU subframeinto the PPDU and complete transmission of the PPDU 602 with the A-MPDUsubframes without the new A-MPDU subframe.

Some embodiments are directed to a non-transitory computer-readablestorage medium that stores instructions for execution by processingcircuitry of an access point station (AP). In these embodiments, theprocessing circuitry may be configured to encode a physical layerprotocol data unit (PPDU) 602 for transmission to a first associatednon-AP station (STA1). The PPDU comprising a physical layer (PHY)preamble 604 followed by a sequence of aggregated MAC Protocol Data Unit(A-MPDU subframe) subframes 606, 608, 610 followed by end-of-file (EOF)padding 612. The processing circuitry may configure the AP to initiatetransmission of the PPDU. When time-critical ultra-low latency (ULL)data for a second associated STA (STA2) becomes available at a mediumaccess control (MAC) layer from an upper layer of the AP duringtransmission of the PPDU, the processing circuitry may encode thetime-critical ULL data in a new A-MPDU subframe 618 and may insert thenew A-MPDU subframe 618 before one of the A-MPDU subframes of the PPDUthat has not yet been transmitted (i.e., before A-MPDU subframe 608).The processing circuitry may configure the AP to complete transmissionof the PPDU 602 with the new A-MPDU subframe 618 followed by all but oneof the remaining A-MPDU subframes for the STA1. In some embodiments, thememory may be configured to store time-critical ULL data. In someembodiments, the processing circuitry may comprise a baseband processor.

Some embodiments are directed to a non-AP station (STA) (STA2). In theseembodiments, for receiving time-critical ultra-low latency (ULL) datafrom an access point station (AP), the STA2 may decode a physical layerprotocol data unit (PPDU) 602 for a first associated non-AP station(STA1) (i.e., another STA). The PPDU may comprise a PHY preamble 604followed by a sequence of aggregated MAC Protocol Data Unit (A-MPDUsubframe) subframes. In these embodiments, the STA2 may decode theA-MPDU subframes to determine if any one of the A-MPDU subframes have aMAC address of the STA2. In these embodiments, the time-critical ULLdata may be encoded in the one A-MPDU subframe that has the MAC addressof the STA2.

In some embodiments, for the one of the A-MPDU subframes have the MACaddress of the STA2, the STA2 may be configured to further decode theA-MPDU subframe and provide the time-critical ULL data to an applicationlayer of the STA2.

In some embodiments, the STA2 may be further configured to establish,with the AP, a time-sensitive networking application that includescommunication of the time-critical ULL data therebetween. In theseembodiments, as part of the establishment of the time-sensitivenetworking application, the AP may be indicated to the STA2 that PPDUsfor STA1 may include A-MPDU subframes with a MAC address of the STA2indicating the time-critical ULL data for STA2.

The following patent applications are incorporated by reference:PCT/US2017/067134, Filed Dec. 18, 2017, Published Jun. 27, 2019 asWO2019/125396, and entitled “ENHANCED TIME SENSITIVE NETWORKING FORWIRELESS COMMUNICATIONS” [Ref No. AA5687-PCT]; PCT/US2018/035868, FiledJun. 4, 2018, Published Dec. 12, 2019 as WO2019/236052, entitled“METHODS AND APPARATUS TO FACILITATE A SYNCHRONOUS TRANSMISSIONOPPORTUNITY IN A WIRELESS LOCAL AREA NETWORK” [Ref No. AA8799-PCT]; U.S.Ser. No. 16/870,156, Filed May 8, 2020, Published as US2020-0267636 A1,entitled “EXTREME HIGH THROUGHPUT (EHT) TIME-SENSITIVE NETWORKING” [RefNo. AC2096-US]

As discussed above, embodiments disclosed herein are directed tocommunicating time-critical ultra-low latency (ULL) data. In someembodiments, an access point station (AP) communicates time-critical ULLdata using aggregated MAC Protocol Data Unit (A-MPDU) preemption. Theseembodiments disclosed herein provide a method that allows the AP totransmit data to other STAs to for time critical ULL data when there notime-critical packet ready to be transmitted. The embodiments providefor improved spectrum efficiency since dedicated resources are not used.Some embodiments provide low latency performance for ultra-low latencyapplication while minimizing the spectrum efficiency loss or the effectto the existing data transmission. In these embodiments, in the downlinkcase, with A-MPDU preemption, the AP is able to suspend the current datatransmission to a STA to insert time critical packet transmission to the(Ultra-low latency) ULL STA in MPDU level. Embodiments disclosed hereinmay be applied to peer-to-peer scenarios. A STA inserts a packet foranother STA while sending packets to the AP.

In these embodiments, assuming that within a BSS, there is time criticaltraffic to be transmitted to a STA referred here as Ultralow latency(ULL) STA. AP will indicate the capability of MPDU preemption forultra-low latency packet transmission in the beacon frame or throughassociation process with the STA. While the AP is sending down-link SUPPDU to a STA and there is short time critical packet for an ULL STA,the AP can defer one A-MPDU subframe and replace it with the short timecritical packet. To minimize the change to the existing PPDU scheduling(i.e., duration of the A-MPDU), the size of the A-MPDU subframe may bekept the same by zero padding if the time critical packet is not longenough to fill the whole A-MPDU subframe.

On the other hand, to avoid the PHY layer change, same PHY layerparameter, which is defined in HE-SIG A or SIG field, such as the MCSlevel, will be used for the A-MPDU subframe to the ULL STA. Here weassume the ULL STA is at the transmission range that can support the MCSthat is being used for the A-MPDU transmission. To reduce the powerconsumption of the ULL STA, the AP and ULL STA may engage in apre-negotiation that whose downlink data the AP may preempt to transmitthe ULL STA. As a result, the ULL STA can ignore the rest of the PPDUonce it decoded that the PPDU is for the STA that is not thepre-negotiated STA. In these embodiments, a “NO ACK” or “delayed ACK”policy may be used for the ULL MPDU. For the non-ULL STA, (e.g., STA1 inFIG. 6 ), the acknowledgement of the ULL MPDU(s) not addressed to thenon-ULL STA may be set to NACK. Similarly, for the ULL STA, theacknowledgement of the non-ULL MPDUs may be set to NACK. The ULL MPDUmay have a different sequence number and the non-ULL STA does not needto send anything response to the ULL MPDU. In general, the new PPDUduration may need to be the same or less than the original since thePPDU duration is specified in the PHY preamble.

In some embodiments, a multi-user (MU) PPDU may be used to communicationtime-critical ULL data. While the AP is sending downlink MU PPDU tomultiple STAs and there is a short time critical packet for an ULL STA.The AP can defer one A-MPDU over one resource unit (RU) and replace itwith the short time critical packet.

To minimize the change to the existing PPDU scheduling, the size of theA-MPDU subframe may be kept the same by zero padding if the timecritical packet is not long enough to fill the whole A-MPDU subframe. Toavoid the PHY layer change, same PHY layer parameter, which is definedin HE-SIG B user specific field for HE MU PPDU case as shown Table 1,such as the MCS level, will be used for the A-MPDU subframe to the ULLSTA. The STA-ID sub field is set to a value indicated from TXVECTORparameter STA_ID to identify the receiver of the data sent over this RU.If this RU is going to be used to insert time critical packet for ULLSTA, this STA_ID should signal the AID of the scheduled STA as well asan indication that it is also going to be used for an ULL STA. These maybe pre-negotiated and known to both the AP and the STAs. For reducingthe power consumption, the number of receiving devices for the same PPDUor resource unit may be as small as possible. An STA_ID may be definedfor a group of devices including the ULL STA and the non-ULL STA.

In these embodiments, the AID may be used in the PHY preamble so thatboth the non-ULL device and the ULL device are notified to receive thePPDU. Since there is a MAC address in each MPDU, the devices can findtheir MPDU(s) by checking the MAC address. For the MPDU with otherdevice's MAC address or a corrupted MPDU, a NACK should be used. Similarto SU PPDU case, “NO ACK” or “delayed ACK” policy may be used for theULL MPDU.

In some embodiments, for acknowledgement for the non-ULL and ULL STAsignaling may be used to adjust the RU allocation of the BA response ofthe ULL STA and the non-ULL STA. In some embodiments, the A-controlfield or TRS may be used to carry the allocation directly in the MPDU ofthe non-ULL STA for the non-ULL STA and in the MPDU of the ULL STA forthe ULL STA. In embodiments that use the TRS, the rules may be changedso that the A-control can be different in all MPDUs within the A-MPDU.In some alternate embodiments, a trigger frame addressed to the ULL STAand a trigger frame addressed to the non-ULL STA may be used to providetwo orthogonal allocations. Alternatively, a single trigger frame inbroadcast address including allocation for non-ULL STA and the ULL STAmay be used, although the scope of the embodiments are not limited inthis respect.

TABLE 1 User Field Format for non-MU MIMO allocation Number Bit Subfieldof bits Description B0-B10 STA-ID 11 Set to a value of the TXVECTORparameter STA_ID (see 26.11.1 (STA_ID)). B11-B13 NSTS 3 If the STA-IDsubfield is not 2046, indicates the number of space- time streams and isset to the number of space-time streams minus 1, Set to an arbitraryvalue if the STA-ID subfield is 2046. B14 Beamformed 1 If the STA-IDsubfield is not 2046, used in transmit beamforming: Set to 1 if abeamforming steering matrix is applied to the waveform in a non-MU-MIMOallocation. Set at 0 otherwise. Set to an arbitrary value if the STA-IDsubfield is 2046. B15-B18 HE-MCS 4 If the STA-ID subfield is not 2046,indicates the modulation and coding scheme: Set to n for HE-MCS n, wheren = 0, 1, 2, . . . , 11 Values 12-15 are reserved. Set to an arbitraryvalue if the STA-ID subfield is 2046. B19 DCM 1 If the STA-ID subfieldis not 2046, indicates whether DCM is used; Set to 1 to indicate thatthe payload of the corresponding user of the HE MU PPDU is modulatedwith DCM for the HE-MCS. Set to 0 to indicate that the payload of thecorresponding user of the PPDU is not modulated with DCM for the HE-MCS.Set to an arbitrary value if the STA-ID subfield is 2046. B20 Coding 1If the STA-ID subfield is not 2046, indicates whether BCC or LDPC isused: Set to 0 for BCC, Set to 1 for LDPC. Set to an arbitrary value ifthe STA-ID subfield is 2046

Alternatively, one RU may be assigned to more than one user whichincludes one or more ULL STAB in a non-MU-MIMO allocation by modifyingthe current 802.11 spec rules that only allows more than one userassigned to one RU in a MU-MIMO allocation. To indicate which RU(s) areused for multiple user multiplexing and the number of multiplexed users,embodiments disclosed herein add a new subfield (i.e., a MU multiplexing(MU-MUX) subfield) that may be nine (9) bits long (based on RUallocation definition in 11ax; the size can be revised based on thedefinition in Wi-Fi8) in the Common field of the HE-SIG-B. Table 2illustrates an RU allocation Subfield. The location of this informationcould be changed for Wi-Fi8 when the preamble is redefined. The MU-MUXsubfield may be encoded to indicate the number of users multiplexed ineach RU that is smaller than 106-tone that is indicated in the RUAllocation subfield. For a 26-tone RU, 1 bit of the MU-MUX subfieldindicates the number of users in the RU up to 2 users (i.e. set to 0 for1 user and 1 for 2 users). For a 52-tone RU, 2 bits of the MU-MUXsubfield indicates the number of users in the RU up to 4 users. For anRU that is smaller than 106-tone non-MU-MIMO allocation is used and foran RU with 106 or 242-tone, MU-MIMO allocation is used.

For example, when the RU Allocation subfield is 1 (00000001), the lastRU is 52-tone and the rest are 26-tone. In the case, the first bit inthe MU-MUX subfield corresponds to the number of users for the first26-tone RU (e.g., if set to 1, then 2 users), and the second bitcorresponds to the number of users in the second 26-tone RU, and so onand the last two bits (B7 and B8) corresponds to the number of users forthe last 52-tone RU (e.g., when set to 3 then, 4 users multiplexed).

When the RU allocation includes a 106 or 242-tone RU or no userallocated RU, the MU-MUX subfield encoding skips those RU locations andonly indicates the RUs that are 26 or 52 tones with at least one user(see table 2). For example, if the RU Allocation subfield is 00011001(i.e., y2y1y0=001), the first 106-tone RU has 2 users using MU-MIMOallocation, and the 2nd RU has no user, and the number of users for the3rd RU (52-tone) is indicated in the first two bits (B0 and B1) in theMU-MUX subfield and the number of users for the last RU (52-tone) isindicated in the B2 and B3 in the MU-MUX subfield.

TABLE 2 RU Allocation Subfield RU Allocation subfield (B7 B6 B5 B4 B3 B2B1 B0) #1 #2 #3 #4 #5 #6 #7 #8 #9  0 (00000000) 26 26 26 26 26 26 26 2626  1 (00000001) 26 26 26 26 26 26 26 52 24-31 106 — 52 52 (00011y₂y₁y₀)

In this way, the ULL STA(s) can use the MCS or PHY parameters that aredifferent than those of the other users in the A-MPDU in the same RU.The rest of the procedure that inserts an ULL packet in the middle of anA-MPDU in the RU remains the same.

FIG. 7 illustrates a functional block diagram of a wirelesscommunication device, in accordance with some embodiments. In oneembodiment, FIG. 7 illustrates a functional block diagram of acommunication device (STA) that may be suitable for use as an AP STA, anon-AP STA or other user device in accordance with some embodiments. Thecommunication device 700 may also be suitable for use as a handhelddevice, a mobile device, a cellular telephone, a smartphone, a tablet, anetbook, a wireless terminal, a laptop computer, a wearable computerdevice, a femtocell, a high data rate (HDR) subscriber device, an accesspoint, an access terminal, or other personal communication system (PCS)device.

The communication device 700 may include communications circuitry 702and a transceiver 710 for transmitting and receiving signals to and fromother communication devices using one or more antennas 701. Thecommunications circuitry 702 may include circuitry that can operate thephysical layer (PHY) communications and/or medium access control (MAC)communications for controlling access to the wireless medium, and/or anyother communications layers for transmitting and receiving signals. Thecommunication device 700 may also include processing circuitry 706 andmemory 708 arranged to perform the operations described herein. In someembodiments, the communications circuitry 702 and the processingcircuitry 706 may be configured to perform operations detailed in theabove figures, diagrams, and flows.

In accordance with some embodiments, the communications circuitry 702may be arranged to contend for a wireless medium and configure frames orpackets for communicating over the wireless medium. The communicationscircuitry 702 may be arranged to transmit and receive signals. Thecommunications circuitry 702 may also include circuitry formodulation/demodulation, upconversion/downconversion, filtering,amplification, etc. In some embodiments, the processing circuitry 706 ofthe communication device 700 may include one or more processors. Inother embodiments, two or more antennas 701 may be coupled to thecommunications circuitry 702 arranged for sending and receiving signals.The memory 708 may store information for configuring the processingcircuitry 706 to perform operations for configuring and transmittingmessage frames and performing the various operations described herein.The memory 708 may include any type of memory, including non-transitorymemory, for storing information in a form readable by a machine (e.g., acomputer). For example, the memory 708 may include a computer-readablestorage device, read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memory devicesand other storage devices and media.

In some embodiments, the communication device 700 may be part of aportable wireless communication device, such as a personal digitalassistant (PDA), a laptop or portable computer with wirelesscommunication capability, a web tablet, a wireless telephone, asmartphone, a wireless headset, a pager, an instant messaging device, adigital camera, an access point, a television, a medical device (e.g., aheart rate monitor, a blood pressure monitor, etc.), a wearable computerdevice, or another device that may receive and/or transmit informationwirelessly.

In some embodiments, the communication device 700 may include one ormore antennas 701. The antennas 701 may include one or more directionalor omnidirectional antennas, including, for example, dipole antennas,monopole antennas, patch antennas, loop antennas, microstrip antennas,or other types of antennas suitable for transmission of RF signals. Insome embodiments, instead of two or more antennas, a single antenna withmultiple apertures may be used. In these embodiments, each aperture maybe considered a separate antenna. In some multiple-input multiple-output(MIMO) embodiments, the antennas may be effectively separated forspatial diversity and the different channel characteristics that mayresult between each of the antennas and the antennas of a transmittingdevice.

In some embodiments, the communication device 700 may include one ormore of a keyboard, a display, a non-volatile memory port, multipleantennas, a graphics processor, an application processor, speakers, andother mobile device elements. The display may be an LCD screen includinga touch screen.

Although the communication device 700 is illustrated as having severalseparate functional elements, two or more of the functional elements maybe combined and may be implemented by combinations ofsoftware-configured elements, such as processing elements includingdigital signal processors (DSPs), and/or other hardware elements. Forexample, some elements may include one or more microprocessors, DSPs,field-programmable gate arrays (FPGAs), application specific integratedcircuits (ASICs), radio-frequency integrated circuits (RFICs) andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements of the communication device 700 may refer to one ormore processes operating on one or more processing elements.

FIG. 8 illustrates a procedure for communicating time-critical ultra-lowlatency (ULL) data using A-MPDU preemption, in accordance with someembodiments. Procedure 800 may be performed by an access point station(AP), although this is not a requirement.

Operation 802 comprises encoding a physical layer protocol data unit(PPDU) for transmission to a first associated station (STA1). The PPDUmay comprise a physical layer (PHY) preamble followed by a sequence ofaggregated MAC Protocol Data Unit (A-MPDU subframe) subframes.

Operation 804 includes initiating transmission of the PPDU.

Operation 806 comprises encoding the time-critical ULL data in a newA-MPDU subframe when time-critical ULL data for a second associated STA(STA2) becomes available at a medium access control (MAC) layer duringtransmission of the PPDU.

Operation 808 comprises inserting the new A-MPDU subframe before one ofthe A-MPDU subframes of the PPDU that has not yet been transmitted.

Operation 809 comprises completing transmission of the PPDU with the newA-MPDU subframe included therein followed by all but one of remainingA-MPDU subframes for the STA1.

The Abstract is provided to comply with 37 C.F.R. Section 1.72(b)requiring an abstract that will allow the reader to ascertain the natureand gist of the technical disclosure. It is submitted with theunderstanding that it will not be used to limit or interpret the scopeor meaning of the claims. The following claims are hereby incorporatedinto the detailed description, with each claim standing on its own as aseparate embodiment.

What is claimed is:
 1. An apparatus of an access point station (AP), theapparatus comprising: processing circuitry; and memory, wherein theprocessing circuitry is configured to: encode a physical layer protocoldata unit (PPDU) for transmission to a first associated station (STA1),the PPDU comprising a physical layer (PHY) preamble followed by asequence of aggregated MAC Protocol Data Unit (A-MPDU subframe)subframes, initiate transmission of the PPDU; wherein when time-criticalultra-low latency (ULL) data for a second associated STA (STA2) becomesavailable at a medium access control (MAC) layer during transmission ofthe PPDU, the processing circuitry is configured to: encode thetime-critical ULL data in a new A-MPDU subframe; and insert the newA-MPDU subframe before one of the A-MPDU subframes of the PPDU that hasnot yet been transmitted; and complete transmission of the PPDU.
 2. Theapparatus of claim 1, wherein the new A-MPDU subframe is encoded toinclude zero-padding to set a size of the new A-MPDU subframe equal to asize of the A-MPDU subframe that has been preempted, and wherein theprocessing circuitry is configured to cause the AP to completetransmission of the PPDU with the new A-MPDU subframe included thereinfollowed by all but one of remaining A-MPDU subframes for the STA1. 3.The apparatus of claim 2, wherein the processing circuitry is furtherconfigured to: encode the PHY preamble to include association identifier(AID) of the STA1; encode the A-MPDU subframes for the STA1 to include aMAC address of the STA1, and encode the new A-MPDU subframe for the STA2to include a MAC address of the STA2.
 4. The apparatus of claim 3,wherein the processing circuitry is further configured to: encode theA-MPDU subframes for the STA1 and indicate ACK; and encode the newA-MPDU subframe for the STA2 and indicate NACK.
 5. The apparatus ofclaim 4, wherein the processing circuitry is further configured toencode the new A-MPDU subframe using one or more physical layer (PHY)parameters indicated in a signal field (SIG) of the PHY preamble of thePPDU.
 6. The apparatus of claim 5, wherein the PPDU is encoded as asingle user (SU) PPDU for the STA1, wherein prior to initiatingtransmission of the PPDU to the STA1, the AP and the STA2 haveestablished a time-sensitive networking application that includescommunication of the time-critical ULL data therebetween, and wherein aspart of establishment of the time-sensitive networking application, theAP has indicated to the STA2 to decode PPDUs for STA1 for time-criticalULL data for STA2.
 7. The apparatus of claim 6, wherein thetime-critical ULL data for the STA2 is received at the MAC layer from anapplication upper layer of the AP, wherein the processing circuitry isconfigured to initiate transmission of the PPDU to the STA1 when thereis no time-critical ULL data available for the STA2 in a transmissionqueue, and wherein when the time-critical ULL data for the STA2 isreceived at the MAC layer from the application upper layer of the APafter transmission of the PPDU has been initiated, the processingcircuitry is configured to delay one of the A-MPDU subframes for theSTA1 and insert the new A-MPDU subframe in the PPDU that includes thatthe time-critical ULL data for the STA2.
 8. The apparatus of claim 4,wherein the time-critical ULL data has a latency requirement of lessthan or equal to one millisecond (ms).
 9. The apparatus of claim 8,wherein the processing circuitry is configured to: insert the new A-MPDUsubframe into the PPDU when transmission of the time-critical ULL dataafter transmission the PPDU would exceed the latency requirement; andrefrain from inserting the new A-MPDU subframe when transmission of thetime-critical ULL data after transmission the PPDU would not exceed thelatency requirement.
 10. The apparatus of claim 9, wherein aftertransmission of the PPDU is initiated and when the time-critical ULLdata for the STA2 does not becomes available during transmission of thePPDU, the processing circuitry is configured to: refrain from encodingthe time-critical ULL data in the new A-MPDU subframe; refrain frominserting the new A-MPDU subframe into the PPDU; and completetransmission of the PPDU with the A-MPDU subframes without the newA-MPDU subframe.
 11. A non-transitory computer-readable storage mediumthat stores instructions for execution by processing circuitry of anaccess point station (AP), the processing circuitry is configured to:encode a physical layer protocol data unit (PPDU) for transmission to afirst associated station (STA1), the PPDU comprising a physical layer(PHY) preamble followed by a sequence of aggregated MAC Protocol DataUnit (A-MPDU subframe) subframes, initiate transmission of the PPDU;wherein when time-critical ultra-low latency (ULL) data for a secondassociated STA (STA2) becomes available at a medium access control (MAC)layer during transmission of the PPDU, the processing circuitry isconfigured to: encode the time-critical ULL data in a new A-MPDUsubframe; and insert the new A-MPDU subframe before one of the A-MPDUsubframes of the PPDU that has not yet been transmitted; and completetransmission of the PPDU with the new A-MPDU subframe.
 12. Thenon-transitory computer-readable storage medium of claim 11, wherein thenew A-MPDU subframe is encoded to include zero-padding to set a size ofthe new A-MPDU subframe equal to a size of the A-MPDU subframe that hasbeen preempted, and wherein the processing circuitry is configured tocause the AP to complete transmission of the PPDU with the new A-MPDUsubframe included therein followed by all but one of remaining A-MPDUsubframes for the STA1.
 13. The non-transitory computer-readable storagemedium of claim 12, wherein the processing circuitry is furtherconfigured to: encode the PHY preamble to include association identifier(AID) of the STA1; encode the A-MPDU subframes for the STA1 to include aMAC address of the STA1, and encode the new A-MPDU subframe for the STA2to include a MAC address of the STA2.
 14. The non-transitorycomputer-readable storage medium of claim 13, wherein the processingcircuitry is further configured to: encode the A-MPDU subframes for theSTA1 and indicate ACK; and encode the new A-MPDU subframe for the STA2and indicate NACK.
 15. The non-transitory computer-readable storagemedium of claim 14, wherein the processing circuitry is furtherconfigured to encode the new A-MPDU subframe using one or more physicallayer (PHY) parameters indicated in a signal field (SIG) of the PHYpreamble of the PPDU.
 16. The non-transitory computer-readable storagemedium of claim 15, wherein the PPDU is encoded as a single user (SU)PPDU for the STA1, wherein prior to initiating transmission of the PPDUto the STA1, the AP and the STA2 have established a time-sensitivenetworking application that includes communication of the time-criticalULL data therebetween, and wherein as part of establishment of thetime-sensitive networking application, the AP has indicated to the STA2to decode PPDUs for STA1 for time-critical ULL data for STA2.
 17. Thenon-transitory computer-readable storage medium of claim 16, wherein thetime-critical ULL data for the STA2 is received at the MAC layer from anapplication upper layer of the AP, wherein the processing circuitry isconfigured to initiate transmission of the PPDU to the STA1 when thereis no time-critical ULL data available for the STA2 in a transmissionqueue, and wherein when the time-critical ULL data for the STA2 isreceived at the MAC layer from the application upper layer of the APafter transmission of the PPDU has been initiated, the processingcircuitry is configured to delay one of the A-MPDU subframes for theSTA1 and insert the new A-MPDU subframe in the PPDU that includes thatthe time-critical ULL data for the STA2.
 18. An apparatus of a non-APstation (STA) (STA2), the apparatus comprising: processing circuitry;and memory, wherein for receiving time-critical ultra-low latency (ULL)data from an access point station (AP), the processing circuitry isconfigured to: decode a physical layer protocol data unit (PPDU) for afirst associated station (STA1), the PPDU comprising a PHY preamblefollowed by a sequence of aggregated MAC Protocol Data Unit (A-MPDUsubframe) subframes, decode the A-MPDU subframes to determine if one ofthe A-MPDU subframes have a MAC address of the STA2, wherein thetime-critical ULL data is encoded in the one A-MPDU subframe that hasthe MAC address of the STA2.
 19. The apparatus of claim 18, wherein whenthe one of the A-MPDU subframes have the MAC address of the STA2, theprocessing circuity is configured to further decode the A-MPDU subframeand provide the time-critical ULL data to an application layer of theSTA2.
 20. The apparatus of claim 19, wherein the processing circuitry isfurther configured to: establish, with the AP, a time-sensitivenetworking application that includes communication of the time-criticalULL data therebetween, and wherein as part of the establishment of thetime-sensitive networking application, the AP has indicated to the STA2that PPDUs for STA1 may include A-MPDU subframes with a MAC address ofthe STA2 indicating the time-critical ULL data for STA2.